So you have mermaids and -men, half-human half-fish (or part [[UnscaledMerfolk seal, dolphin, whale]]) who come with their own [[MermaidProblem set of problems]]. Then you have FishPeople who are humanoid but scaly, think of the Film/CreatureFromTheBlackLagoon.

Then there's these characters. They look so human that they could wander unnoticed down a city street, but can breathe and live underwater. In fact many prefer to live underwater as that is often where they were born, and they only come to the surface to complain that HumansAreTheRealMonsters for polluting the ocean, or to do some superheroing. In fact if they are unused to life on land they may find themselves acting like a FishOutOfWater.

This can include anything from an individual who has this ability as a special quirk, to whole civilizations of these who may or may not live in an UnderwaterCity.

Often overlaps with WalkDontSwim, WaterIsDry, and WaterIsAir.

----!!Examples

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[[folder:Anime and Manga]]* ''Not'' the mermaids themselves, but the Panthalassa race in ''MermaidMelodyPichiPichiPitch'' is composed of these. Most of them, however, don't have a choice but to live underwater (until the seal on their civilization breaks, that is), and we only see a few of them, many of whom we're supposed to assume are human until we realize that they've survived instances where they should have drowned. They also have nebulous, unexplained superpowers and CreepyCoolCrosses. Huh.* The merrows of ''{{Manga/Berserk}}'' have the ability to shift from a more traditional mermaid body to a fully humanoid form that's capable of walking on land and having children with human men. This is how a lone island girl named Isma was conceived. [[spoiler:And it turns out that Isma is herself a merrow who's capable of switching between both forms.]]* The people of Shioshishio in ''Anime/NagiAsuALullInTheSea'', are no different from the land dwellers, except an extra covering that they need to periodically soak with seawater, so they wouldn't dry up.* The plot of the anime movie ''Coral Reef Legend: Elfie of the Blue Seas'' has main protagonist Elfie as one of these ''and'' [[LastOfTheirKind the last of her kind]], as all her people were exterminated years ago.* ''[[Manga/ShinryakuIkaMusume Ika Musume]]'', arguably, since when she isn't manipulating things with her tentacles, she appears to be a normal girl with a NiceHat and a weird hairstyle.[[/folder]]

[[folder:Comics]] * DCComics has Comicbook/{{Aquaman}}, Aqualad, and their kin. Somewhat of a mixed example, as Atlantis also includes more traditional mermaids (Lori Lemaris) and others (Lagoon Boy, Blubber) who are animal/sea-life mixtures. * MarvelComics has Namor the {{Sub-Mariner}} who has slightly pointy ears and wings on his feet as he can also fly, but looks much closer to human than fish.** Namor's people also normally have blue skin, but he's half-human and a ''mutant'' to boot (hence the wings which are not natural to either side of his lineage).* The Top Cow comic ''ComicBook/{{Fathom}}'' is about a member of a race of water-based humanoid {{Elemental Shapeshifter}}s who have this among their abilities.* The Aqualanians from ''[[ComicBook/{{SwordQuest}} Swordquest: Waterworld]],'' a race of undersea merpeople; aside from their yellow-green skin and green hair, they look like humans (complete with legs) and are capable of breathing air.[[/folder]]

[[folder:Film]] * At the end of ''Film/{{Splash}}'' Allen becomes one of these so he can be with the more typical mermaid love Madison.* [[http://www.imdb.com/title/tt0055844/ There's]] an old Soviet romantic sci-fi film called ''Chelovek-Amfibiya (The Human Amphibian)'', in which an oceanologist's son with sick lungs [[WeCanRebuildHim was given]] [[BioPunk additional implants]] [[ArtisticLicenseBiology derived from the gils of a young shark]]. [[ExactlyWhatItSaysOnTheTin He can survive on land, but mostly sticks to the sea, where he's more comfortable with breathing.]] The main plot point of the movie is [[spoiler: the gradual deterioration of his ability to breathe atmospheric air and the need to forever leave dry land and live purely in the sea]].* The Mariner in ''Film/{{Waterworld}}'', played by Kevin Costner, has gills behind the ears.[[/folder]]

[[folder:Literature]]* The titular character of ''Literature/PercyJacksonAndTheOlympians'' what with him being a demigod son of Poseidon and all.* ''Literature/TheSecretOfPlatform13'' has Melisande, a merrow who is proud of having feet and continually points them out, for some reason touchy about the idea that people will mistake her for a mermaid. * The rifters from Peter Watts' ''Literature/RiftersTrilogy'' are modified humans (cybernetics and genetic engineering are used) who can survive in deep sea conditions. In fact, they prefer the sea to staying in their confined UnderwaterBase.* Electra of the ''NotQuiteAMermaid'' series. JustifiedTrope - she was born human, but was found after a storm by merfolk and given magical sea powder so that she could breathe and live underwater.[[/folder]]

[[folder:LiveActionTelevision]] * ''Series/TheManFromAtlantis'' is another example. The only indication of his nature was webbed hands.* The titular heroine of ''Series/OceanGirl'' looked fully human.* In later seasons of ''Series/SeaQuestDSV'', the character Tony Piccolo is a human who was modified with gills along his sides (and probably RequiredSecondaryPowers to allow him to survive deep-sea pressure) but otherwise looks completely normal.* In ''Series/TheOuterLimits1995'' episode "The New Breed", a scientist is injected with nano-robots who "correct" his cancer and myopia. When he and his friend test the limits of the robots abilities, one of the tests is to see how long the man can stay underwater. The nano-robots misinterpret this by giving the man gills so he can breathe, seriously squicking him out.* An episode of ''Series/DarkAngel'' had a couple of transgenics who looked perfectly human, except for the gills coming out of their backs and their inability to speak. They also laid eggs.* ''Series/MakoMermaidsAnH2OAdventure'' is mostly about these.[[/folder]]

[[folder:Mythology]]* The oceanids, nereids, and naiads of Myth/GreekMythology look entirely human, though perhaps more beautiful than mortals. * This is the typical form of mermaids in the Literature/ArabianNights and other Middle Eastern folklore; the only difference between them and land-dwelling humans is that they (and in one story, their children with humans) can breathe underwater.* [[SelkiesAndWereseals Selkies]] of Faroese and [[{{Scotireland}} Scotirish]] folklore wear a sealskin as a wetsuit and take human form when they shed it. The Faroese story "The Seal Wife" is about a man who steals a selkie woman's wetsuit and locks it up so that she can't go back to the sea.[[/folder]]

[[folder:TabletopGames]]* The ''Stormwreck'' source-book for ''TabletopGame/DungeonsAndDragons 3.5'' has aventi, who, in a justified version of this trope, are actual aquatic humans. They were once a great empire who sunk beneath the waves during a cataclysm, but their god mutated their bodies to be able to survive underwater. Apart from a few distinct features, such as unusual colored hair and skin tones, and fins on their wrists and ankles, they are pretty much identical to humans, and the book explicitly states they can easily disguise themselves as such.* ''TabletopGame/{{Traveller}}'': The Nexines who actually are human merfolk. They are a race genetically engineered for underwater mining. ** Their [[MeaningfulName name]] too is like the name Nexie which is a kind of water fay.[[/folder]]

[[folder:VideoGames]]* Naiads in TheWitcher. They walk literally naked (yes, right in the game, with all the details), have greenish skin and dark green hair (yes, pubic hair too), but otherwise absolutely human. Dryads and Lady of the Lake closely resemble them in appearance, except that Lady's best parts are [[GodivaHair covered with her long hair]].* In ''VideoGame/TalesOfLegendia'' there's the Ferines, an aquatic race that looks perfectly human despite the fact that [[spoiler: they evolved completely underwater; their planet had NO dry land until humans from space came and raised it from the ocean]].* ''VideoGame/{{Aquaria}}'' has Li become this shortly after Naija finds him. It's a handy side benefit of your FishPerson girlfriend having magic powers, though it might only work if they're in close proximity -- Li puts his old diving helmet back on if Naija decides to leave him behind somewhere. [[HalfHumanHybrid Their son]] might also count.* In ''SoulNomadAndTheWorldEaters'', the Nereids are a pretty clear example with a female ''OneGenderRace'' bonus as well. There are some minor differences, though; they have blue skin and hair, and small breasts so as to swim through the water better. They also have to mate with humans (or possibly Sepp, this isn't ever made clear) to produce offspring, too. Their leader is a more traditional mermaid, but this is never given an explanation.[[/folder]]

[[folder:WesternAnimation]]* ''WesternAnimation/{{SpongeBob SquarePants}}'' gives us Mermaid Man and Barnacle Boy, parody {{Exp|y}}ies of Adam West era Batman and Robin. ** The show eventually explained that they ARE normal humans. The starfish Mermaid Man wears on his face magically keeps him alive and was a gift from some friendly mermaids (ergo the name.) Likewise, Mermaid Man gave Barnacle Boy the ability to breathe water....by forcing him to ingest a bunch of barnacles. ** [[spoiler: Wrong. It was actually eating slightly-overcooked popcorn that gave them powers.]]* Marina and her people (all of whom are mute) from the 1964 series ''[[Series/{{Stingray 1964}} Stingray]]''.[[/folder]]

[[folder:Webcomics]]* The seatrolls of ''Webcomic/{{Homestuck}}'' look exactly the same as any other troll except for having fins attached to their cheeks. (Fans sometimes depict the fins as [[UnusualEars coming out of their ears]] instead.)[[/folder]]----